Hitherto, in blanket printing, a printing surface of a printing blanket (corresponding to a transferring blanket) is pressed against a printing master plate (corresponding to a printing plate) so that ink, which is applied onto the printing master plate in a pattern corresponding to a printing pattern, is transferred onto the printing blanket. Subsequently, the printing surface of the printing blanket, onto which the ink is transferred, is pressed against a surface to be printed so that the transferred ink is transferred onto the surface to be printed. In this manner, the printing pattern is printed on the surface to be printed.
For example, in the related art, the printing blanket is an elastic body, such as elastic (flexible) silicon rubber, in which a silicon oil is mixed, and is formed into a substantially hemispherical shape (bullet shape) or a substantially semi-cylindrical shape (bullet shape in cross section). The printing blanket is pressed against the printing master plate having a flat surface shape and the surface to be printed having a curved surface shape, to thereby transfer the ink onto the surface to be printed. Therefore, in particular, a distal end of the printing blanket (lowermost point or lowermost line) and a periphery of the distal end are deteriorated or damaged due to damage caused by the operation of pressing the printing blanket against the printing master plate, a protrusion of the surface to be printed when the printing blanket is pressed against the printing surface, or other adverse effects. Due to the deterioration of or the damage to the limited region of the printing blanket, the printing blanket cannot be used.
Further, in order to fit the printing blanket in conformity with the surface to be printed, it is necessary to form the printing blanket softly (corresponding to formation of the printing blanket so as to have a small elastic modulus and to be easily elastically deformed). With this, when the printing surface of the printing blanket is pressed against the printing master plate so that the printing blanket is deformed, the silicon oil mixed in the printing blanket seeps out to a surface of the printing blanket. At this time, the ink applied to the printing master plate is not easily transferred from the printing master plate onto the printing blanket so that the printing pattern printed on the surface to be printed may be faded or blurred.
Further, through repetition of the printing, the ink or the silicon oil is excessively deposited on the printing master plate, thereby staining the printing master plate. The printing blanket is pressed against the stained printing master plate, thereby transferring the stains onto the printing blanket. The printing is performed using the stained printing blanket, thereby staining the printing pattern printed on the surface to be printed.
Further, when the printing is performed using the printing blanket, the silicon oil component seeping out from the elastic body of the printing blanket adheres to the surface to be printed. When the surface to be printed with the silicon oil component adhering thereto is to be coated, the coating is repelled by the silicon oil component. With this, a desired coating layer is not formed on the surface to be printed.
Meanwhile, when the content of the silicon oil in the silicon rubber forming the printing blanket is reduced to obtain a harder silicon rubber, it is difficult to perform the printing on a curved surface in a wide region. Therefore, the printing is limited in a small region so that the designability may be degraded. Further, when the printing is to be performed in the wide region, it is necessary to repeat the printing in the small region a plurality of times, thereby increasing the printing cost.
In view of the problems described above, in the related art, there is used a printing blanket having a printing surface obtained by bonding a replaceable elastic sheet to a surface of an elastic body formed of soft silicon rubber. In the printing blanket having such a configuration, the sheet is replaceable when the printing surface is deteriorated, damaged, or affected with other external factors, and the seeping of the silicon oil from the soft silicon rubber can be suppressed.
Further, in the invention disclosed in Patent Literature 1, “a side surface of an elastic body is pressed against a sheet placed on a flat surface, to thereby manufacture a printing blanket being the elastic body having the sheet bonded to the side surface.” With this, an inexpensive and replaceable sheet can be bonded to a surface of the printing blanket, onto which the printing pattern is transferred from the printing master plate. Further, when the sheet bonded to the printing blanket is deteriorated or damaged, the sheet can be released from the elastic body, and a new sheet can be bonded by the same step. Thus, the elastic body of the printing blanket can be repeatedly used.
Further, in the invention disclosed in Patent Literature 1, the sheet is bonded to the elastic body while gradually increasing the contact surface between the elastic body and the sheet from a ridge line of the elastic body to a periphery of the ridge line. Therefore, entry of air bubbles between the elastic body and the sheet is suppressed when the sheet is bonded to the surface of the elastic body.